/ultraplan deterministically fails: "seed bundle import: firestore: not found"

Summary

/ultraplan <prompt> fails immediately at session creation with the same error every time. The CLI never opens a web session. Three back-to-back retries over ~20 minutes produced byte-identical errors, so this looks deterministic, not transient.

Reproduction

$ /ultraplan add production js, ts and python materials plan
◇ ultraplan
Starting Claude Code on the web…
ultraplan: session creation failed — seed bundle: seed bundle import: failed to import files: error executing request: file not found: {"code":"not_found","message":"file to import not found: error retrieving file to import: firestore: not found"}

Reproduced 3/3 attempts. Identical error string each time.

Environment

• Claude Code: 2.1.143
• OS: macOS 26.5 (Darwin 25.5.0)
• Shell: zsh
• Working directory: a clean git repo on main branch
• Plan file present at ~/.claude/plans/<name>.md (~30 KB, well-formed markdown)
• gh auth healthy; /ultrareview and other CLI features unaffected

What I tried

1. Re-running /ultraplan immediately — same error
2. Refining the plan file content (size ~10 KB → ~30 KB) and re-running — same error
3. Verified working tree was clean, on main, plan file exists and is readable
4. Other plan files in ~/.claude/plans/ have shipped fine previously, so the local CLI path and plans directory aren't the issue

The "firestore: not found" suffix suggests a cloud-side lookup against a reference that was never written (or was GC'd) before the import ran — looks like an Anthropic infra bug, not a local-config issue. Filing per the support flow.